With four countries in the World’s top 10 largest national emitters of CO2, Asia is a highly important region in the global carbon budget. China surpassed the USA as the largest national emitter of CO2 since 2006. While the emissions of the USA and the European Union are coming to a halt or even decrease, the emissions from China and India are still increasing rapidly (with about 240% for China and 190% for India between 1990 and 2000). One of the reasons for this is the export of our production to China.

Two publications in Nature Communications and Nature Scientific Reports with contributions from researchers from Wageningen University investigate the role of Asia in the global carbon cycle. “Our studies focus on the complete carbon budgets of Asia and China respectively,” Ingrid van der Laan-Luijkx of Wageningen University says. “The concentrations of CO2 in the Earth’s atmosphere are not only a result of the emissions by fossil fuel combustion, but these are partly offset by CO2 uptake by the biosphere and oceans. Our studies include therefore besides the CO2 emissions from fossil fuel combustion, also the CO2 uptake by the Asian land biosphere, and emissions and uptake related to land use change.”

With new observations of CO2 concentrations becoming available from Asia, including campaigns as Contrail where observations are made onboard commercial aircraft with regular flights from Japan to other Asian countries, the possibilities to study the carbon budget of this important region have increased. Wouter Peters and Ingrid van der Laan-Luijkx (both of the Meteorology and Air Quality chair group) contributed to those studies with results from the atmospheric inverse model CarbonTracker, developed at their chair group in collaboration with partners in the USA and China, with support from NWO's ‘China Exchange Programme’. CarbonTracker is a data assimilation system that tracks CO2 exchange between the atmosphere and the biosphere and oceans, using atmospheric measurements of CO2 concentrations. Wouter Peters: “In a region with rapid changes in fossil fuel emissions, the emission inventories reported by governments are less reliable, therefore CO2 observations from monitoring networks in Asia are essential to study the carbon cycle.”

The first study shows that the Asian land biosphere was a net sink of CO2 of 0.46 PgC/yr (petagram carbon) between 1996 and 2012, and this sink increased during this period. About 17% of the CO2 emitted from fossil fuels was taken up by the Asian biosphere. This sink was mainly located in East Asia. The second study showed that the biospheric CO2 sink of China was 0.45 PgC/yr in 2006–2009.

Deforestation in Southeast Asia is a large source of CO2, releasing an estimated average of 0.23 PgC per year for 1990–2007, while, East Asian ecosystems appear to be a substantial sink of CO2, taking up an estimated 0.16–0.33 PgC per year due to afforestation/reforestation and regional climate change, especially in Southern China.